Semiconductor components, such as dice, packages and interconnects are being made thinner than previous generation components. At the same time, electrical and packaging requirements for semiconductor components are becoming more stringent. Typically, semiconductor components are thinned from the back side at the wafer level using a process such as grinding or chemical mechanical planarization (CMP). For example, a standard 200 mm (8 inch) diameter semiconductor wafer has a thickness of about 725 μm. During fabrication, the wafer can be thinned to a thickness of about 100 μm or less.
Back side thinning of a semiconductor wafer can cause problems during wafer level processes, during component fabrication processes, and in the singulated components as well. One problem is that the thinned wafer can bow due to stresses generated by the circuitry formed on the circuit side (face) of the wafer. In this case, a thinned wafer oriented circuit side up can bow upward in the shape of a smile (i.e., generally convex shape), causing carrier adhesion, wafer handling and alignment issues during component fabrication. A singulated component from a thinned wafer can also bow upward towards the circuit side, and from the corners towards the center of the component. Bowed components can be more difficult to mount, particularly in flip chip and stacking applications. For example, terminal contacts on a bowed flip chip or stacked component can pull away from mating electrodes or contacts on a substrate or adjacent component.
Another problem caused by thinning is that the back side of a thinned semiconductor component can have a smooth, polished surface, reducing the number of defect sites. The defect sites can trap contaminants in the semiconductor substrate and can also act as carrier generation and recombination centers. The contaminants can adversely affect the minority carrier lifetime electrons of the semiconductor devices changing functionality and certain defect mechanisms. One technique for attracting contaminants is to deposit a gettering agent, such as a spin-on dopant, on the back side of a component. However, relatively high temperatures (e.g., >800° C.) are required to drive the dopant into the semiconductor substrate. A thinned semiconductor component typically includes circuitry on the circuit side, which cannot be subjected to high temperatures. For this reason, thinned semiconductor components do not usually employ an extrinsic back side gettering layer due to the difficulties in applying this layer. In addition, thinned semiconductor components can have different electrical characteristics and a different functionality than full thickness components.
In view of the foregoing, improved thinned semiconductor components, and improved methods for fabricating thinned semiconductor components are needed in the art. However, the foregoing examples of the related art and limitations related therewith, are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.